Israeli Prime Minister Ehud Olmert on Sunday (May 20) convened his cabinet to discuss possible expansion of the military operation in Gaza aimed at stopping militants from launching rockets into southern Israel. "We cannot accept the fact that women, children, and Israeli citizens are attacked by terrorists, day-in, day-out by missiles from Gaza, and the world is expecting us not to do anything. It is impossible, and we will defend our citizens forcefully," said Israeli Welfare Minister Isaac Herzog before entering the meeting. "The cabinet will be convened today in order to continue the discussion that started last week. And there are options - different options of actions, which should be taken by the government of Israel and by our army. Part of them have been taken the last weekend, which have been very effective, and I believe in the options before us there are possibilities in order to really reduce drastically the number of missiles they can launch on Israel," Israeli Housing Minister Meir Sheetrit told Reuters. Israel began a wave of air strikes against Hamas targets in Gaza starting on Wednesday and senior Israeli officials said they were considering taking tougher measures. "If the measured steps we are taking, in the political and military sphere, do not bring about the desired calm, we will be forced to intensify our response," Israeli Prime Minister Ehud Olmert said at the beginning of the cabinet meeting. Olmert said the military operations during the past week have been effective. "The security system is operating against the terrorists who bare responsibility for these attacks, tens of them were killed in the past few days. Hamas men are paying and will pay a very heavy personal price for these assaults against the people of Sderot and the people of the surrounding communities," Olmert said. Israeli Minister of Defence Amir Peretz travelled by helicopter to a military base in southern Israel to assess operations Sunday. "Undoubtedly, this is a new situation. Hamas carrying out regular offensive activity against Israel constitutes a new situation that obliges Israel to provide determined answers that will lead to a reduction in Qassam fired, and a reduction in the attempts to hurt the sovereignty of the state of Israel," Peretz told reporters. At the Israeli border with Gaza, heavy artillery has been positioned. Tanks, armoured vehicles, and some amount of ground troops have crossed the border in recent days into the northern edges of Gaza, but a major ground offensive has not yet been launched by Israeli forces. The Israeli bombing campaign against Hamas has killed at least 21 Palestinians since Wednesday. Local residents said the dead included at least five civilians. Four Palestinians were killed in air strikes on Saturday. They came on a day when more than a dozen rockets were fired into Israel by Palestinian militants. Nobody was hurt in Israel by the rockets, although they caused some damage in towns bordering Gaza. Israel's air strikes have plunged the Palestinians deeper into turmoil after nine days of fierce internal fighting verging on civil war between ruling Hamas Islamists and President Mahmoud Abbas's secular Fatah faction. Hamas and Fatah negotiators agreed in Egyptian-brokered talks to a new ceasefire which began at 1200 GMT on Saturday. Previous ceasefire agreements fell apart within hours and it was unclear whether the new one would hold, although an agreed swap of some 30 hostages taken by both sides was completed late on Saturday night, officials from both sides said. At least 49 Palestinians have been killed in the last 10 days of internal fighting between Hamas and Fatah.